CAREER: Elucidating Fuel Spray Atomization Physics: Setting a Path for High-Efficiency Clean Combustion

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1653687 GenzaleThis project will develop a new experimental method for measuring fuel spray properties under practical combustion-relevant environments. This work is critical for the advancement of high-efficiency clean combustion engines. These measurements stand to transform our understanding of fuel sprays from empirical to fundamental, because the physical mechanisms of spray breakup under practical combustion conditions have yet to be measured or proven. Determination of the governing mechanisms of fuel spray atomization will help researchers develop more accurate computer models, which will be used as a predictive tool for the discovery of new high-efficiency clean combustion strategies. Educational activities in this project aim to encourage broader participation of women in research careers and to develop a diverse engineering workforce who can innovate the grand challenge solutions that our future world will depend on.The primary research objectives of this proposal are to: 1) measure the joint droplet Sauter Mean Diameter (SMD) and liquid volume fraction field of atomized high-pressure fuel sprays under combustion-relevant conditions, and 2) test un-validated literature hypotheses on the physical mechanisms that lead to interface instabilities and jet breakup in high-pressure fuel sprays, including aerodynamic forces, liquid turbulence, cavitation, and/or orifice flow effects. The research approach is centered on the employment of a new state-of-the-art high-pressure optically-accessible combustion chamber recently commissioned within my laboratory at Georgia Tech via institutional support, which enables optical spray and combustion measurements at up to 100 bar and 900 K. A two-wavelength tomographic extinction measurement is developed to enable simultaneous 3-D measurements of droplet SMD and liquid volume fraction distribution in practical fuel sprays under combustion-relevant conditions. Hypothesis testing of the governing atomization mechanisms in fuel sprays is conducted via measurements with controlled orifice geometry and fuel properties over a wide range of ambient gas density conditions.